The disclosure of Japanese Patent Application No. 2001-118515 filed on Apr. 17, 2001 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of Invention
The invention relates to an intake apparatus and methods of an internal combustion engine that controls an air current formed in a combustion chamber by controlling the opening and closing of an intake current control valve that is positioned downstream of a throttle valve in an intake pipe.
2. Description of Related Art
As a related technology, Japanese Patent Application Laid-Open No. 6-248959 discloses an intake apparatus of an internal combustion engine where an intake current control valve is positioned in an intake pipe downstream of the throttle valve and upstream of the fuel injection apparatus.
This intake apparatus incorporates a swirl control valve (intake current control valve) positioned in an intermediate portion of the intake passage, and produces intake air swirls by closing a swirl control valve body that has a cutout. The apparatus thereby increases the combustion speed, improves the rate of fuel consumption during a low-load operation and stabilizes the engine revolution during a lean air-fuel ratio operation.
With regard to using the control valve as discussed above, various configurations have been proposed. In order to form a stable air current during closure of the control valve, it is necessary to precisely set the area and position of a constricted portion of the intake pipe that is formed by closing the valve. However, with the control valve configurations of the related technologies, it is difficult to control the amount of intake air leaking through a gap between an outer periphery of the valve and an interior wall portion of the intake pipe.
Furthermore, in order to reduce the gap between the outer periphery of the valve and the interior wall portion of the intake pipe for the purpose of reducing the leakage of air through the gap therebetween, it becomes necessary to mount the valve in the intake pipe with high precision. If the gap is reduced, but a necessary precision in mounting the valve to the intake pipe is not obtained, the valve may contact the interior wall of the intake pipe and cause damage. Moreover, the valve may become stuck in the intake pipe and, subsequently, cannot be opened or closed. As a result, the internal combustion engine equipped with the control valve fails to achieve stable combustion, thereby degrading the emission characteristic and drivability of the vehicle incorporating the internal combustion engine.
Accordingly, it is an object of the invention to provide an intake apparatus of an internal combustion engine equipped with an intake control valve which is capable of producing air currents with stability by controlling the air leakage that occurs through a gap between an outer periphery of the valve and an interior wall portion of the intake pipe during closure of the valve.
More specifically, the intake control valve is disposed upstream of the combustion chamber in an intake pipe that leads an intake air current into a combustion chamber, and that has a section that intersects a longitudinal axis of the intake pipe. The intake control valve controls an air current to a combustion chamber through the opening and closing of the valve. Furthermore, the intake control valve has an open portion for passing intake currents only through the open portion in the closed state.